Switchboard plug



Jan. 13, 1953 A. J. vwn-:R

SWITCHBOARD PLUG Filed May 27, 1949 y u a lll/l'- Illlllllr FIG. 2

VVE/v70@ A. J. W/ER ATTO/WSV Patented Jan. 13, 1953 UNITED STATES PATENT OFFICE SWITCHBOARD PLUG Anthony J. Wier, Cranford, N. J., asslgnor to Bell Telephone Laboratories, Incorporated, New York, N. Y., a corporation of New York Application May 27, 1949, Serial N o. 95,723

2 Claims.

This invention relates to switchboard plugs and more particularly to telephone switchboard plugs having more than three conductors.

Conventional three-conductor telephone switchboard plugs have a small diameter tip portion which is a requirement so that the switchboard jacks with which such plugs are used can be closely spaced to permit as many jacks as possible in a given area of a switchboard face.

The introduction of four-wire toll line circuits in the telephone plant has created the need for switchboard plugs and jacks having more than three, for example ve, conductors but retaining the same diameter of the tip portion of the plugs and the same switchboard jack spacing as is used with the conventional threeconductor plugs and jacks.

An object of this invention is the provision of switchboard plugs having more than three conductors, without increase in the diameter of the tip portion of the plugs as compared to the diameter of the tip portion in the conventional three-conductor telephone switchboard plugs.

A feature of this invention relates to an arrangement of contact pieces on the tip of a plug, insulated from the plug sleeve and body and also from each other and each terminating within the body of the plug and arranged therein for connection to a flexible electrical conductor of a switchboard cord.

Another feature relates to a means for guiding the plug into the sleeve of a switchboard jack in a predetermined manner so that the contact pieces in the tip of the plug will engage springs of the jack in the same definite relationship upon every insertion of the plug in the jack.

The invention will 'be more fully understood from a consideration of the embodiment illustrated in the accompanying drawing in which:

Fig. 1 is a plan view of a switchboard plug made in accordance with the features of this invention, in which the shell of the plug is partially cut away to show the arrangement within the body of the plug;

Fig. 2 is a sectional view showing the plug cut in a plane along the line 2-2 of Fig. l;

Fig. 3 is an end elevational view of the tip end of the plug of Fig. 1;

Fig. 4 is a cross-sectional view of the plug in a plane along the line 4-4 of Fig. 1;

Fig. 5 is a cross-sectional view of the plug in a plane along the line 5-5 of Fig. 1; and

Fig. 6 is a perspective view of a portion of the plug of Fig. 1 with the plug inserted in the sleeve 0f a switchboard jack, portions only of the jack frame and jack springs being shown.

Referring now to the drawing, the switchboard plug I0 has a metallic tubular body II of uniform diameter with a tip I2 of lesser uniform diameter, body II and tip I2 being formed, advantageously, in one piece. A sleeve I3 composed of phenolic fibre or similar insulating material covers almost the entire length of body II. Sleeve I3 is held in place on body II by a machine screw I4 which threads into body II through a countersunk clearance hole in sleeve I3, in such a manner that the edge of the screw head is below the surface of sleeve I3. i

Four contact members or ns I5, I6, I1, I8 protrude from the end of tip I2 and are imbedded in insulating material 20 which may be, for example, a phenolic condensation product. The insulating material 2D extends through vthe bore o f tip I 2 into the interior portion of the body II of the plug I0. An insulatingring 2| is formed as part of the protruding insulation material 20 and has a diameter equal to the diameter of tip I2. End 22 of the insulation material 20 within body Il lies at a point about mid-way of the axial length of body II. An inner shell I9 lies within body Il as a spacer required due to the dilerence in the bores'of body II and tip I2.

Fins I5, I6, Il, I8 have Shanks 23, 24, 25, 26. respectively, which extend through insulation material 20 into the interior of body II. An insulating piece 21 composed of, for example', a phenolic condensation product, lies within body II upon a nat surface 28 of the insulation material 20. A metal plate 29 lies uponinsulating piece 2'I. End 30 of shank 24 is inserted through a hole in plate 28 and is soldered or brazed to plate 28. Plate 28 carries a machine screw 3| which threads into it for use in attaching a conductor of a switchboard cord to plate 28. End 32 of shank 23 protrudes from insulation material 20 and is formed for attaching a conductor of a switchboard cord thereto, as for example, by soldering or other suitable means. End 33 of shank 26, and end 34 of shank 25 also protrude from the insulation material 20 and are formed in a manner similar to end 32 of shank 23 for attaching a conductor of a switchboard cord to each. An opening 35 is provided in body Il to give access to the interior thereof for attaching the conductors of a switchboard cord to screw 3l and shank ends 32, 33, 34.

Fins I5, I6, Il, I8 are each provided with a hook 46 which projects longitudinally along the axis ot plug I with the hook pointing toward the body II. Hooks 49 engage the outer end of insulation 20 which is countersunk or beveled at an angle with the axis of plug I0, this angle corresponding to the angle of the inwardly projecting faces of hooks 49. rThe engagement of hooks 49 with the beveled end. of. insulation 20 secures theetipends ofi'ns I5,` I8, I.1,`. I8 toprevent their movement outward from the axis of plug I0. Plastic material is moulded on the end' of insulation 20 between fins I5, I6, I.1 I8V to form a round end to the plug.

Fins I 5, I6, I1, I8 areA alsoprovided with detents 36, 31, 38, 39, respectivelmasi-.show-n in. Fig. 1 and Fig. 3. These detents areY forengagefment with the angular end portions 5951, 52 53, respectively, of jack springs 45; 46, 41, 43; shown in Fig. 6.

A metallic pin 40 protrudes from tip I2 near the. insulating; ring, 2I. Pin 49 is for guiding the plug tip= I2v intfraslOty 4I of. the. sleeve 42 of a. switchboard.jack43,.of.which.sleeve 42 and parts.Y of aframe 44 and.. jack springs 45,46, 41,.48are shown in Fig. 6.

The inner surface of thefend Dortionnf body II has. a threaded: portion.. 54. as shown. in` Fig. 2. which is provided for screwing theplugv Illonto` theL end'portion `of; they braided outer covering. ofA a. switchboard cordnot shown. The. connection betweenthe sleeve-conductor of the-cord and the body, II.` ofV plug I0 is made in the conventional. manner by bendingV this. sleeve conductor. of. the: cordn backwards. along, the fbraided. outer: covering. of the cord before the. plugj is-screwedontofthe; cord.: This forces the sleeve. conductor of the cord? intointimate Contact Withbody- I-I ofplug I0,\ and provides. the fifth conductor for the plug: Ill...

The. operation. of the l plug or this` invention. is-

byinsertion of the. tip portion-.thereof in the; sleeve42-of: jack 43fvvithI pin 40. insertedrinslot 4I, or sleeve.V 42; This pin: insuresthat the contact fins I5, I-I,` I1, I8of the plugcan only make. contactW-ith certain of the. jack springs 45,. 46, 41,` 48. Specically, fin- I5. can only. make conf` tact with spring 45,.n I6. with spring 46,A finF I1v withA spring 41` and fin I8,With spring 48;A UntilA pin lill-entersislot 4I the tipportionof. the` plug. cannot enter jack sleeve 42 far enoughffor. any of. theifins I; I6, I-1 or I8 tof make contact with any-of the jack. contact springs45, 46, 41, 48.

When pin 48- enters, slot.4.I and.l the,l tipv portion` of plug IIl is`A pushed.v into jack sleeve. 42, the-flns I5, I6, I1, I8- pressagainst the ends: oiY

jack springs,45,` 46, 41,y 4'81w`hich are bentout-A wardly from the axiszof.- jack sleeve 42. Asthe iinsr move intotheiack 43 -eachnlifts the.. end.. of'.' its.I related jack: spring slightly. W-hexrthe. shoulder of sleeve II reaches, the face of jacksleevev 43. the ns I5, I6, IFI, Ifhave. progressed.r

into jack 43 to a position whereby the angular end portions 56, 5I, 52, 53 of jack springs 45, 46, 41, 48 drop into detents 38, 31, 38, 39, respectively, due to their spring tension, and this spring tension of the angular end portions of the jack springs in the detents secures the plug in the jack until sumcient pull is exerted to overcome thisV` tension and; allowthe withdrawal of the plugfroml the jack.

While this invention has been disclosed With reference to one specific embodiment, it is, of course, understood that modifications may be made inthe detail assembly Without departing from the' scope-andzspirit of the invention.

What; is;l claimedy is:

1. A-n electrical connecting plug comprising an outer shell of insulating material, a metal -sleeve positioned in said shell and extending some distance: beyond one end thereof, an insulating member positioned in said sleeve and having a portion thereof extending beyond said end thereof, aquad of conducting members embeddedin said insulating member extending longitudinally therewithY and having at one end thereof notched iin-like portions projecting radially beyondv thesurface of the exposedportion of `said insulating, member and arranged in space quadrature, the. inner ends of said conducting membersrhaving. connectionsV thereon for securing, electrical conductors thereto.

2.v An electrical connecting plug comprisingan outer shell of insulating material, a metal sleeve.

positionedin'saidshell and extending some dis.-Vv tance. beyondk the end. thereof, an insulating member positionedr in. said. sleevev and' having, a-

portion thereof extendingbeyondthe endethereof',

a quad of. conducting members. embedded in said insulating member extending longitudinallytherewith and having at oneend thereof iinlike portions projecting radially beyondy the'sur-A face of the exposed portion of said insulating member and arranged in space quadrature, said ns having staggered notches thereinA for. the` reception of contact springs, the inner endsof said conducting members having connections thereon for securing electrical conductors there-Y to, and means on said. sleeve for making an.elec trical connection thereto;

ANTHONY J; WIER.

REFERENCES CITED The following references are-oi record in the nie of this patent:

Number Name Date.

1,808,902. Mueller .June 9', 1931" 1,841,468 Ford Jan. 19, 1932 2,220,810 Bright Nov. 5,1940v 2,285,535 Saunders Mar. 18, 1941 2,359,634. Franklin Crct..3,-194i` 

